Receiver circuit and method using selectively variable amplification for receiving time signals from different transmitters

Abstract

A time signal carrying encoded time information transmitted at a transmission frequency from any one of plural time signal transmitters is received, amplified, and evaluated to acquire the time information. The transmission frequency of the received time signal is determined (provided is the time information signal's just emitted frequency f), and an amplification factor of the amplification of the signal is adjusted depending on the transmission frequency. A receiver circuit for a radio-controlled clock in this regard includes at least one amplifier having a variable amplification factor that is adjustable dependent on the frequency of the received time signal.

Description

PRIORITY CLAIM[0001]This application is based on and claims the priority under 35 U.S.C. §119 of German Patent Application 103 57 200.7 filed on Dec. 8, 2003, and German Patent Application 10 2004 002 776.5 filed on Jan. 20, 2004, the entire disclosures of both of which are incorporated herein by reference.FIELD OF THE INVENTION[0002]The invention relates to a receiver circuit for a radio-controlled clock for receiving time signals transmitted from various different time signal transmitters, with an amplifier circuit for amplifying the received signals and a filter circuit for filtering the received signals. The invention further relates to a method of acquiring time information from the received time signal by means of such a receiver circuit, as well as a radio-controlled clock including such a receiver circuit.BACKGROUND INFORMATION[0003]It is conventionally known to provide time reference information in time signals that are transmitted by radio transmission from a time signal t...

AI Technical Summary

Benefits of technology

The present invention provides a receiver circuit for a radio-controlled clock that can make the receiver sensitivity more independent of the transmission frequency of the received time signals. This means that the receiver can make the necessary adjustments to the amplification factor of the amplifier circuit so that it can accurately receive and evaluate any time signals, regardless of the frequency of the signal. This results in a more reliable and secure method of acquiring time information from received time signals, without consuming excessive power or energy. The invention also includes a method for automatically recognizing the transmission frequency of the received time signal, and a control and evaluating arrangement that preloads the amplifier with a specified adjustment of the amplification factor for a particular known transmission frequency.

Problems solved by technology

This requirement poses new problems for the reception, amplification, decoding, and evaluation of the respective time signals.

In this regard it is problematic, however, that the amplifier of the receiver circuit conventionally has a constant fixed amplification factor, so that it always amplifies the respective received time signal with the same amplification, regardless whether the received time signal has a relatively lower received signal strength or amplitude or a relatively higher signal strength or amplitude.

Thus, the amplified signal output by the amplifier does not always have the optimum signal level for its further processing.

This can lead to problems and errors in the decoding and the subsequent evaluation of the time data encoded in the time signal.

The problem arises, however, that other time signals having a higher transmission frequency and thus typically a higher received signal amplitude, will be amplified at the same high amplification factor, leading to over-amplification of such signals.

This has various disadvantages, in comparison to a circuit with a lower amplification factor that would be completely adequate for such received signals having a high received signal amplitude.

This directly leads to higher costs of the circuit for providing a higher power amplifier, and especially also causes a higher power consumption of the amplifier circuit, because the higher amplification factor requires higher amplifier currents and thus directly a higher power consumption.

Thus, in the above described systems, the amplifier designed for the “worst case scenario”, leads to a relatively short operating life of the batteries, or the need to frequently recharge the accumulators.

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